Confirm before navigation with React Router

component.jsx

import React from 'react'

class MyComponent extends React.Component {
  
  componentDidMount() {
    this.props.router.setRouteLeaveHook(this.props.route, this.routerWillLeave)
  }

  routerWillLeave(nextLocation) {
    // return false to prevent a transition w/o prompting the user
    if(!window.confirm('Are you sure you want to leave?')) {
      return false
    }
    
    // or return a string to allow the user to decide
    return nextLocation
  }
  
  // ...
  
}

export { MyComponent }